. >> today i see a man who is full of life and energy. i'actually have a hard time keeping up with peter. when i see things like that, and i remember the way patients were before the surgery, it's like witnessing a miracle, because you see they really do have their lives back. it's quite something to witness. >> narrator: but for people with parkinson's, the hope engendered by stories like peter sauer's proved short-lived. a year after peter's procedure, a series of fetal transplants at the university of colorado, utilizing a different surgical technique than the halifax team, yielded deeply disappointing results. while some recipients showed modest improvement, others wound far worse, unable to even control their own bodies. >> even though some patients recovered, some patients recovered too much. in other words, they started to show excessive movements rather than just enough. so instead of being helped, they were actually made worse. >> narrator: it was a demoralizing setback, and, despite the halifax success, served to largely freeze